Fluorinated ion exchange polymers having carboxylic acid functional groups are known in the art. One principal use of such polymers is as a component of a membrane used to separate the anode and cathode compartments of a chloralkali electrolysis cell. Such membrane can be in the form of a reinforced or unreinforced film or laminar structure which may incorporate other polymers which may or may not carry other functional groups, such as fluorinated ion exchange polymers having sulfonyl functional groups which are in ionic or ionizable form.
It is desirable for use in a chloralkali cell that the membranes provide for operation at low voltage and high current efficiency, and thereby at low power consumption, so as to provide products of high purity at low cost, especially in view of today's steadily increasing cost of energy. It is further desirable that membranes having such performance characteristics are capable of providing those characteristics over an extended period of time, as such membranes themselves are expensive to make, and replacement additionally interrupts the electrolysis process.
It is therefore important to provide such membranes having improvement in said performance characteristics, and ways to improve the characteristics of known membranes. Such are the objects of this invention.